No description available.

polyhomeotic is a gene of the Polycomb-group required for proper segment determination in Drosophila. Genetic and molecular analysis has shown that ph has a repetetive structure. The DNA sequence presented here shows that ph consists of a direct tandem duplication with very high sequence conservation. Analysis of the sequence has revealed several conserved open reading frames and splice junctions, putative transcriptional promoter and terminator sequences, polyadenylation signals and translational start signals. In addition, the DNA sequence shows that ph contains a zinc finger sequence in each repeat. This suggests that ph may encode a DNA-binding protein. / Science, Faculty of / Zoology, Department of / Graduate

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2015. / RBBP6 is an E3 Ubiquitin ligase protein with a U-box motif. It interacts with p53 and Rb and is linked to several cellular functions. SNAMA is the Drosophila RBBP6 homolog, but is less characterized than its vertebrate counterparts. Gene expression studies on Drosophila have a potential to advance the knowledge on molecular mechanism underlying genotoxic stress. Previous studies have shown that SNAMA plays a critical role as an apoptosis suppressor and possibly in responses to genotoxic stress. The molecular basis for this is, however, unknown. Initially, two isoforms were identified by bioinformatics and one (Snama A) experimentally as well. Here, we confirm experimentally the existence of the second isoform (Snama B). We also show that these are differentially expressed during development and when the organism undergoes genotoxic stress. Total RNA samples were used to demonstrate gene expression by using Reverse Transcriptase Polymerase Chain Reaction. Using samples collected at different stages of development and from adult flies treated with the DNA damaging agent, irinotecan, it is shown that these isoforms are differentially expressed throughout development and upon genotoxic stress. This knowledge may help to understand the functional role SNAMA plays in normal physiology and in response to genotoxic stress. Furthermore, the results show that SNAMA is involved in a potentially beneficial intervention whereby the glycolytic pathway is bypassed by the addition of methyl pyruvate.

Gemin5 是運動神經元綜合體(SMN Complex)的其中一個組件，這綜合體的主要功能是控制小型胞核核糖核蛋白(UsnRNPs)的合成。這些小型胞核核糖核蛋白組合成剪接核糖核酸前體(pre-mRNA)的剪接體(Spliceosome)，使核糖核酸分子可以用來翻譯成蛋白質。失去運動神經元綜合體功能引致脊髓肌肉萎縮症。果蠅是其中一個用作研究人類疾病重要的生物。更重要的是，部分組成運動神經元綜合體的組件也存在於果蠅。是次研究是利用遺傳方式在果蠅內研究Gemin5 的同源基因-- rigor mortis (rig) 的作用。果蠅帶有rig 突變基因表現神經肌肉接頭(neuromuscular junction)上的缺陷和異常的運動行為。這表明，rig 的功能可能與神經退化性疾病有關。為了進一步了解rig 的功能途徑(functional pathway)，已進行了一個利用移除突變體的基因過濾實驗，研究鎖定了 12 個染色體部份可能和rig 有基因上的相互作用，進一步研究與rig 有相互作用的基因有助於了解rig 的功能及研究脊髓肌肉萎縮症的發病機制。 / Gemin5 is a component of the Survival of Motor Neuron (SMN) complex, which is a protein complex regulating biogenesis of various Uridine-enriched small nuclear ribonucleoproteins (UsnRNPs). These UsnRNPs form the molecular machinery spliceosome, which mediates pre-messenger RNA splicing, an important mechanism before an mRNA molecule can be used to translate proteins. Loss-of-function of the SMN complex is now known to cause the neurodegenerative disease, Spinal Muscular Atrophy. Drosophila is one of the well-characterized model organisms for studying human diseases. More importantly, components of the SMN complex are also found in Drosophila. Here, I studied the function of rigor mortis (rig), the Gemin5 orthologue, in Drosophila using a genetic approach. Drosophila carrying mutations in the rig gene show defects in the neuromuscular junction (NMJ) and display abnormal motor behavior. This suggests that the function of rig may link to the neurodegenerative disease. To further characterize the function of rig, a genetic screen was carried out. Twelve chromosomal regions encoding possible rig-interacting genes were identified. Further characterization of these rig-interacting genes may help us better understand the function of rig. / Detailed summary in vernacular field only. / Cheng, Yat Pang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 120-125). / Abstracts also in Chinese. / ABSTRACT --- p.i / ABSTRACT IN CHINESE --- p.ii / ACKNOWLEDGEMENT --- p.iii / LIST OF ABBREVIATIONS --- p.iv / LIST OF FIGURES --- p.v / LIST OF TABLES --- p.vi / TABLE OF CONTENTS --- p.vii / Chapter CHAPTER 1. --- INTRODUCTION / Chapter 1.1 --- Introduction of rigor mortis / Chapter 1.1.1 --- Orthologue of Gemin5 in Drosophila --- p.1 / Chapter 1.1.2 --- Published Phenotypic Analyses of rig Mutants --- p.1 / Chapter 1.2 --- Introduction of Gemin5 / Chapter 1.2.1 --- Introduction of Gemins --- p.4 / Chapter 1.2.2 --- Structural Properties of Gemin5 --- p.4 / Chapter 1.2.3 --- Gemin5-interacting partners --- p.7 / Chapter 1.2.4 --- Gemin5 as a Component of the Survival of Motor Neuron (SMN) Complex --- p.7 / Chapter 1.2.5 --- Function of the SMN Complex and Spinal Muscular Atrophy --- p.11 / Chapter 1.3 --- Drosophila as a Model Organism / Chapter 1.3.1 --- Advantages of Using Drosophila as a Model Organism --- p.11 / Chapter 1.3.2 --- Neuromuscular Junction of Drosophila --- p.15 / Chapter 1.4 --- Aim of the Present Study --- p.19 / Chapter CHAPTER 2. --- MATERIALS AND METHODS / Chapter 2.1 --- Drosophila Culture / Chapter 2.1.1 --- Culture Medium --- p.20 / Chapter 2.1.2 --- Drosophila Stocks and Crosses Maintenance --- p.20 / Chapter 2.1.3 --- Larvae Collection --- p.21 / Chapter 2.1.3.1 --- Reagents --- p.21 / Chapter 2.1.3.2 --- Procedures --- p.21 / Chapter 2.2 --- Cell culture / Chapter 2.2.1 --- Reagents --- p.23 / Chapter 2.2.2 --- Drosophila S2R⁺ Cell Culture --- p.24 / Chapter 2.2.3 --- Establishment of Stable S2R⁺ Cells --- p.24 / Chapter 2.3 --- Genomic Polymerase Chain Reaction (PCR) / Chapter 2.3.1 --- Reagents --- p.25 / Chapter 2.3.2 --- Genomic DNA Extraction from a Single Larva --- p.26 / Chapter 2.3.3 --- Primer Design --- p.26 / Chapter 2.3.4 --- Polymerase Chain Reaction (PCR) --- p.27 / Chapter 2.4 --- Behavioral Assay / Chapter 2.4.1 --- Stable S2R⁺ Cell Staining --- p.29 / Chapter 2.4.1.1 --- Reagents --- p.29 / Chapter 2.4.1.2 --- Procedures --- p.30 / Chapter 2.4.2 --- Larvae Staining --- p.31 / Chapter 2.4.2.1 --- Reagents --- p.31 / Chapter 2.4.2.2 --- Larvae Dissection --- p.32 / Chapter 2.4.2.3 --- Larval Muscle Staining --- p.33 / Chapter 2.4.2.4 --- Larval Neuromuscular Junction Staining --- p.33 / Chapter 2.5 --- Microscopy / Chapter 2.5.1 --- Light Microscopy --- p.34 / Chapter 2.5.1.1 --- Microscopic Observation of Larval Movement --- p.34 / Chapter 2.5.1.2 --- Quantification of Larval Contraction Rate --- p.34 / Chapter 2.5.1.3 --- Quantification of Larval Travelling Distance --- p.34 / Chapter 2.5.2 --- Fluorescence Microscopy --- p.35 / Chapter 2.5.2.1 --- Microscopic Observation of Larval Muscle --- p.35 / Chapter 2.5.2.2 --- Microscopic Observation of Stable S2R⁺ Cells --- p.35 / Chapter 2.5.3 --- Confocal Microscopy --- p.36 / Chapter 2.5.3.1 --- Microscopic Observation of Larval Neuromuscular Junction --- p.36 / Chapter 2.5.3.2 --- Quantification of Larval Neuromuscular Junction --- p.36 / Chapter 2.6 --- Generation of transgenic fly lines expressing rig transgene / Chapter 2.6.1 --- Polymerase Chain Reaction --- p.36 / Chapter 2.6.2 --- Agarose Gel Electrophoresis --- p.38 / Chapter 2.6.2.1 --- Reagents --- p.38 / Chapter 2.6.2.2 --- Procedures --- p.39 / Chapter 2.6.3 --- Restriction Digestion --- p.39 / Chapter 2.6.4 --- Ligation Reaction --- p.39 / Chapter 2.6.5 --- Bacterial Transformation --- p.40 / Chapter 2.6.5.1 --- Reagents --- p.40 / Chapter 2.6.5.2 --- Procedures --- p.40 / Chapter 2.6.6 --- Bacterial Glycerol Stock for Long-term Storage --- p.41 / Chapter 2.7 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and Immunoblotting / Chapter 2.7.1 --- Reagents --- p.41 / Chapter 2.7.2 --- Lysate Preparation of Stable S2R⁺ Cells, Adult Fly Heads and Larvae --- p.44 / Chapter 2.7.2.1 --- Stable S2R+ Cells --- p.44 / Chapter 2.7.2.2 --- Adult Fly Heads --- p.44 / Chapter 2.7.2.3 --- Larvae --- p.45 / Chapter 2.7.3 --- SDS-Polyacrylamide Gel Electrophoresis --- p.45 / Chapter 2.7.4 --- Immunoblotting --- p.45 / Chapter CHAPTER 3. --- PHENOTYPIC CHARACTERIZATION OF RIG MUTANT / Chapter 3.1 --- Introduction --- p.48 / Chapter 3.2 --- Re-balancing of rig Mutant Fly Lines Over the Cy; Tb Compound Balancer for Genotype Identification --- p.48 / Chapter 3.3 --- Verification of Model Genotype --- p.49 / Chapter 3.4 --- rig Mutant Larvae Displayed Abnormal Motor Behavior / Chapter 3.4.1 --- Contraction Rate of rig Mutant Larvae --- p.54 / Chapter 3.4.2 --- Traveling Distance of rig Mutant Larvae --- p.56 / Chapter 3.5 --- rig Mutant Larvae Showed Normal Body Wall Musculature --- p.58 / Chapter 3.6 --- rig Mutant Larvae Displayed Defects in the Neuromuscular Junction / Chapter 3.6.1 --- rig Mutant Larvae Showed Branching Defects --- p.60 / Chapter 3.6.2 --- rig Mutant Larvae Showed Fewer Boutons Number --- p.62 / Chapter 3.7 --- rig Mutant Larvae Showed Normal Active Zone Pattern --- p.64 / Chapter 3.8 --- Discussion --- p.66 / Chapter CHAPTER 4. --- A GENETIC SCREEN TO IDENTIFY GENES THAT INTERACT GENETICALLY WITH RIG / Chapter 4.1 --- Introduction --- p.71 / Chapter 4.2 --- Candidates and Design of the Screen --- p.72 / Chapter 4.3 --- Re-balancing of Deletion Lines Over the Cy; Tb Compound Balancer --- p.75 / Chapter 4.4 --- Identification of Chromosomal Regions That Genetically Interact With rig --- p.75 / Chapter 4.5 --- Identification of NMJ Genes That Genetically Interact With rig --- p.80 / Chapter 4.6 --- Discussion --- p.83 / Chapter CHAPTER 5. --- ATTEMPTS TO INVESTIGATE RIG FUNCTION IN PRE-AND POST-SYNAPTIC REGIONS OF THE NMJ / Chapter 5.1 --- Introduction --- p.89 / Chapter 5.2 --- Transgenic Rescue Experiment by Transgenic Expression of rig in rig Mutant / Chapter 5.2.1 --- Design of the Rescue Experiment --- p.90 / Chapter 5.2.2 --- Construct of pUAST-rig-FLAG --- p.93 / Chapter 5.2.3 --- Construct of the pUAST-myc-rig --- p.98 / Chapter 5.3 --- Tissue Specific Knockdown of rig expression --- p.102 / Chapter 5.4 --- Discussion --- p.105 / Chapter CHAPTER 6. --- ESTABLISHMENT OF AN INDUCIBLE S2R⁺ CELL MODEL FOR RIG OVEREXPRESSION / Chapter 6.1 --- Introduction --- p.108 / Chapter 6.2 --- Detection of Rig Protein in S2R⁺ Cells by Immunoblotting --- p.111 / Chapter 6.3 --- Detection of Rig Protein in S2R⁺ Cells by Immunostaining --- p.111 / Chapter 6.4 --- Detection of RNA in Immunopurified Rig Protein --- p.113 / Chapter 6.5 --- Discussion --- p.115 / Chapter CHAPTER 7. --- GENERAL DISCUSSION --- p.117 / References --- p.120 / Appendices --- p.126

"November 2002" / Bibliography: p. 177-194. / 194 p. : ill., plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences, 2003

Amyotrophic lateral sclerosis (ALS) is a major neurodegenerative disease caused by the death of motor neurons leading to paralysis. Mechanisms underlying the pathogenesis of the disease remain unknown but with the identification of causative genes from ALS patients, some processes have been linked to the disease. One of these genes is VAPB, a highly conserved protein involved in lipid transfer, vesicle metabolism and synaptic morphology. We modeled in Drosophila the disease-linked P56S mutation (DVAP-P58S) and observed with the expression of this allele neurodegeneration in the eye and loss of motor performance. These phenotypes provide an excellent opportunity to use fly’s genetics to find novel genetic interactors of DVAP and understand ALS pathomechanism. Therefore, we carried out a large scale genetic screen by crossing the ALS model with a collection of P-element overexpression lines. After the analysis of 1183 lines, we obtained 71 modifier lines that suppress DVAP-induced neurodegeneration and 14 lines that enhance this phenotype, decreasing furthermore the eye size and viability of the offspring. To confirm that the effect of modifier lines was caused by a specific gene, we validated them with independent alleles of those genes. Using different sources, we were able to confirm the effect of 63 of the 85 modifiers, providing a strong confirmation of their effect. When we studied the effect of the modifier genes co-expressed with DVAP-P58S in the nervous system, we detected that 46 lines presented the same modifying effect in adult viability and 58 in the motor performance of the adult offspring. Considering the stronger readouts, we obtained 42 genes as novel high confidence DVAP genetic interactors. To understand furthermore the way they are affecting DVAP neurodegeneration, we carried out a series of bioinformatic analyses using Drosophila and human databases. Lipid droplets, vesicle metabolism and cell proliferation appear as the most important categories found in the screen, all processes conserved when analysed with human orthologs of the modifiers. Further characterisation of the endocytosis-linked modifier Rab5 and the predicted DVAP-interactors Rab7 and Rab11, showed that the suppression effect is not only confirmed in vivo but is also conserved in human tissue from ALS patients. These data validate our genetic screen and at the same time open novel opportunities to understand ALS mechanisms and find possible therapeutic targets.

A central question in neuroscience is to identify the roles of genes in behavior. A deeper understanding of genetic influences on behavior would provide insight into the relative impact of innate vs. environmental influences on behavior, as well as improve treatments for neurological diseases. To elucidate the role of genes in behavior, we must not only identify specific genes involved, but also determine the cell types in which they act and the mechanisms by which they exert their influence. In Chapter 2 of this thesis, I found that circadian genes comprising the circadian clock were not necessary in “master clock neurons”, or Pdf+ neurons, for circadian locomotor rhythms. I also identified a small subset of neurons in which disruption of these circadian genes completely abolishes Drosophila circadian behavior. In Chapter 3, I describe the role of a glial gene, ebony, in the regulation of Drosophila courtship and sleep behavior. In addition to identifying the cell types in which ebony acts to regulate these behaviors, I also provide insight into the underlying mechanism of neurotransmitter modulation. The results in this chapter highlight the consideration of non-neuronal cells in the brain when examining the roles of genes in behavior. Together, the results in Chapter 2 and 3 further our understanding of how genes in small populations of cells influence a myriad of conserved Drosophila behaviors.

Lam Wun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 140-153). / Abstracts in English and Chinese. / ABSTRACT --- p.i / ACKNOWLDGEMENT --- p.iii / TABLE OF CONTENT --- p.iv / ABBREVIATIONS --- p.x / LISTS OF TABLES --- p.xi / LISTS OF FIGURES --- p.xii / Chapter 1. --- INTRODUCTION / Chapter 1.1 --- Neurodegeneration and triplet repeat diseases --- p.1 / Chapter 1.2 --- Polyglutamine diseases --- p.2 / Chapter 1.3 --- Polyglutamine nuclear inclusions --- p.4 / Chapter 1.3.1 --- Kinetics of polyglutamine nuclear inclusion formation --- p.4 / Chapter 1.3.2 --- Roles of protein inclusions in neurodegeneration --- p.7 / Chapter 1.4 --- Polyglutamine pathogenic pathways --- p.8 / Chapter 1.4.1 --- Protein depletion theory --- p.9 / Chapter 1.4.2 --- Induction of apoptotic pathways --- p.13 / Chapter 1.5 --- Previous study on NI proteins --- p.14 / Chapter 1.6 --- Drosophila model for studying polyglutamine diseases --- p.15 / Chapter 1.6.1 --- Drosophila model for studying human diseases --- p.15 / Chapter 1.6.2 --- GAL4/UAS gene expression system --- p.15 / Chapter 1.6.3 --- Drosophila polyglutamine models --- p.17 / Chapter 1.7 --- Objectives of the study --- p.21 / Chapter 2. --- MATERIALS AND METHODS / Chapter 2.1 --- Drosophila genetics --- p.22 / Chapter 2.1.1 --- Drosophila culture --- p.22 / Chapter 2.1.2 --- GAL4/UAS gene expression system --- p.22 / Chapter 2.1.3 --- Eye phenotypic analysis --- p.25 / Chapter 2.1.4 --- Polyglutamine fly models --- p.25 / Chapter 2.1.5 --- Generation and characterization of GFP-polyglutamine transgenic fly models --- p.25 / Chapter 2.2 --- Proteomic identification of nuclear inclusion proteins --- p.26 / Chapter 2.2.1 --- Proteomic identification of NI proteins by SDS-insolubility of NIs --- p.26 / Chapter 2.2.2 --- Proteomic identification of NI proteins by FA-solubility of NIs --- p.27 / Chapter 2.2.2.1 --- Approach overview --- p.27 / Chapter 2.2.2.2 --- Sample preparation for two-dimensional gel electrophoresis --- p.27 / Chapter 2.2.2.3 --- Two-dimensional gel electrophoresis --- p.29 / Chapter 2.2.2.4 --- Polyacrylamide gel staining --- p.31 / Chapter 2.2.2.5 --- Computer analysis of 2D patterns --- p.31 / Chapter 2.2.2.6 --- In-gel trypsin digestion --- p.32 / Chapter 2.2.2.7 --- Mass spectrometric analysis --- p.33 / Chapter 2.2.3 --- Detection of NIs by flow cytometry --- p.34 / Chapter 2.3 --- SDS-polyacrylamide gel electrophoresis (SDS-PAGE) --- p.34 / Chapter 2.3.1 --- Sample preparation for SDS-PAGE --- p.34 / Chapter 2.3.2 --- SDS-PAGE --- p.35 / Chapter 2.4 --- Immunodetection --- p.36 / Chapter 2.4.1 --- Electroblotting --- p.36 / Chapter 2.4.2 --- Western blotting --- p.36 / Chapter 2.4.3 --- Filter trap assay --- p.37 / Chapter 2.5 --- Sav antibody production --- p.38 / Chapter 2.5.1 --- Sav peptide synthesis --- p.38 / Chapter 2.5.2 --- Rabbit immunization --- p.38 / Chapter 2.6 --- Cryosectioning and immunostaining of adult fly heads --- p.39 / Chapter 2.7 --- Alcohol dehydrogenase assay --- p.40 / Chapter 2.8 --- Semi-quantitative reverse transcription- Polymerase Chain Reaction --- p.41 / Chapter 2.8.1 --- Total RNA preparation from fly heads --- p.41 / Chapter 2.8.2 --- Reverse transcription- Polymerase Chain Reaction (RT-PCR) --- p.41 / Chapter 2.9 --- Reagents and buffers --- p.42 / Chapter 3. --- RESULTS / Chapter 3.1 --- Transgenic polyglutamine fly models --- p.48 / Chapter 3.1.1 --- Characteristics of MJD polyglutamine fly model --- p.48 / Chapter 3.1.1.1 --- Overexpression of expanded truncated human MJD proteins in Drosophila causes eye degeneration --- p.49 / Chapter 3.1.1.2 --- Overexpression of expanded truncated human MJD proteins in Drosophila results in nuclear inclusion formation --- p.49 / Chapter 3.1.1.3 --- Formic acid dissolves fly polyglutamine nuclear inclusions --- p.51 / Chapter 3.1.1.3.1 --- Formic acid dissolves fly polyglutamine NIs as shown by Western blot analysis --- p.51 / Chapter 3.1.1.3.2 --- Formic acid dissolves fly polyglutamine NIs as shown by filter trap assay --- p.53 / Chapter 3.1.2 --- Summary --- p.55 / Chapter 3.2 --- Proteomic identification of nuclear inclusion (NI) proteins --- p.56 / Chapter 3.2.1 --- Proteomic identification of NI proteins by SDS-insolubility of NIs --- p.56 / Chapter 3.2.2 --- Proteomic identification of NI proteins by FA-solubility of NIs --- p.63 / Chapter 3.2.2.1 --- Two-dimensional gels showing differential protein spots as potential NI proteins --- p.63 / Chapter 3.2.2.2 --- NI protein candidates identified by the 2D approach --- p.75 / Chapter 3.2.3 --- Study of polyglutamine NI proteins by flow cytometry analysis --- p.90 / Chapter 3.2.3.1 --- Detection of fly polyglutamine NIs by flow cytometry --- p.90 / Chapter 3.2.3.2 --- Characterization of a new GFP-polyglutamine fly model --- p.92 / Chapter 3.3 --- Characterization of the nuclear inclusion protein candidates --- p.96 / Chapter 3.3.1 --- Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) --- p.96 / Chapter 3.3.1.1 --- Confirmation of GAPDH as a NI protein --- p.97 / Chapter 3.3.1.2 --- Discussion --- p.97 / Chapter 3.3.2 --- Receptor of activated protein kinase C (RACK1) --- p.99 / Chapter 3.3.2.1 --- Confirmation of RACK1 as a NI protein --- p.99 / Chapter 3.3.2.1.1 --- Colocalization of RACK1 with NIs --- p.99 / Chapter 3.3.2.1.2 --- Formic Acid extracts RACK1 from NIs --- p.101 / Chapter 3.3.2.2 --- Reduction of soluble RACK1 protein level in polyglutamine fly --- p.101 / Chapter 3.3.2.2.1 --- Soluble RACK1 protein level reduced in polyglutamine fly --- p.101 / Chapter 3.3.2.2.2 --- RACK1 transcript level remains unchanged in polyglutamine fly --- p.103 / Chapter 3.3.2.3 --- Overexpression of RACK 1 partially suppresses polyglutamine degeneration --- p.105 / Chapter 3.3.2.4 --- Discussion --- p.107 / Chapter 3.3.3 --- Warts (Wts) --- p.111 / Chapter 3.3.3.1 --- Overexpression of Wts partially suppresses polyglutamine degeneration --- p.111 / Chapter 3.3.3.2 --- Wts mutant slightly enhances polyglutamine degeneration --- p.113 / Chapter 3.3.3.3 --- Genetic analysis of Warts pathway in polyglutamine pathogenesis --- p.113 / Chapter 3.3.3.3.1 --- Overexpression of Salvador partially suppresses polyglutamine degeneration --- p.116 / Chapter 3.3.3.3.2 --- Hpo mutant slightly enhances polyglutamine degeneration --- p.119 / Chapter 3.3.3.3.3 --- Overexpression of DIAP1 partially suppresses polyglutamine degeneration --- p.119 / Chapter 3.3.3.4 --- Discussion --- p.121 / Chapter 3.3.4 --- Alcohol dehydrogenase (Adh) --- p.122 / Chapter 3.3.4.1 --- Adh activity is reduced in polyglutamine flies --- p.122 / Chapter 3.3.4.2 --- Overexpression of Hsp70 partially restores the reduced Adh activity in polyglutamine flies --- p.122 / Chapter 3.3.4.3 --- Discussion --- p.125 / Chapter 3.3.5 --- Genetic analysis of other NI protein candidates --- p.127 / Chapter 3.3.5.1 --- Overexpression of CG7920 protein partially suppresses polyglutamine degeneration --- p.127 / Chapter 3.3.5.2 --- Pten dsRNA slightly enhances polyglutamine degeneration --- p.129 / Chapter 3.3.6 --- Summary --- p.131 / Chapter 4. --- DISSCUSSION / Chapter 4.1 --- Protein depletion theory --- p.133 / Chapter 4.2 --- Comparison of different approaches for identification of NI proteins --- p.134 / Chapter 4.3 --- Long-term significance --- p.136 / Chapter 4.4 --- Future studies --- p.137 / Chapter 4.4.1 --- Characterization of other NI protein candidates --- p.137 / Chapter 4.4.2 --- Study of NI proteins by an alternative approach --- p.137 / Chapter 4.4.3 --- Study of NI proteins using other polyglutamine fly models --- p.137 / Chapter 5. --- CONCLUSION --- p.139 / Chapter 6. --- REFERENCES --- p.140

Chau Wing-Kam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 92-101). / Abstracts in English and Chinese. / Abstract --- p.I / Abstract (Chinese version) --- p.III / Acknowledgement --- p.IV / List of Abbreviations --- p.VIII / List of Tables --- p.IX / List of Figures --- p.X / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Neurodegenerative diseases --- p.2 / Chapter 1.2 --- Tauopathies --- p.5 / Chapter 1.3 --- Function and structure of Tau --- p.9 / Chapter 1.4 --- Post-translational modifications of Tau --- p.13 / Chapter 1.5 --- Tau protein kinases --- p.17 / Chapter 1.6 --- Tau protein kinase inhibitors --- p.19 / Chapter 1.7 --- Drosophila model of Tauopathies --- p.20 / Chapter 1.8 --- Aims of study --- p.24 / Chapter Chapter 2 --- Materials and methods / Chapter 2.1 --- Drosophila manipulation / Chapter 2.1.1 --- Drosophila genetics --- p.26 / Chapter 2.1.2 --- External fly eye and adult wing morphology examination --- p.27 / Chapter 2.1.3 --- Study of fly wings deformation on Tau kinase overexpression --- p.27 / Chapter 2.2 --- RNA extraction / Chapter 2.2.1 --- Method --- p.28 / Chapter 2.2.2 --- Buffers and reagents --- p.29 / Chapter 2.3 --- Reverse transcription-PCR / Chapter 2.3.1 --- Method --- p.30 / Chapter 2.3.2 --- Buffers and reagents --- p.31 / Chapter 2.4 --- SDS-Polyacrylamide gel electrophoresis / Chapter 2.4.1 --- Method --- p.31 / Chapter 2.4.2 --- Buffers and reagents --- p.32 / Chapter 2.5 --- Western blotting / Chapter 2.5.1 --- Method --- p.32 / Chapter 2.5.2 --- Buffers and reagents --- p.33 / Chapter 2.6 --- Phosphatase treatment of proteins / Chapter 2.6.1 --- Method --- p.34 / Chapter 2.6.2 --- Buffers and reagents --- p.34 / Chapter 2.7 --- Sequential extraction of proteins / Chapter 2.7.1 --- Methods --- p.35 / Chapter 2.7.2 --- Buffers and reagents --- p.36 / Chapter 2.8 --- Sarkosyl extraction of proteins / Chapter 2.8.1 --- Method --- p.37 / Chapter 2.8.2 --- Buffers and reagents --- p.37 / Chapter 2.9 --- Immunostaining / Chapter 2.9.1 --- Method --- p.38 / Chapter 2.9.2 --- Buffers and reagents --- p.38 / Chapter 2.10 --- Lithium treatment of flies / Chapter 2.10.1 --- Method --- p.39 / Chapter 2.10.2 --- Buffers and reagents --- p.40 / Chapter 2.11 --- Quantitation of Lithium ion by atomic absorption spectrometry / Chapter 2.11.1 --- Method --- p.40 / Chapter 2.12 --- Statistical analysis --- p.41 / Chapter Chapter 3 --- Results / Chapter 3.1 --- GAL4/UAS gene expression system in transgenic fly / Chapter 3.1.1 --- Introduction --- p.43 / Chapter 3.1.2 --- Results --- p.47 / Chapter 3.1.3 --- Discussion --- p.52 / Chapter 3.2 --- Tau phosphorylation and Tau-induced toxicity in transgenic fly / Chapter 3.2.1 --- Introduction --- p.52 / Chapter 3.2.2 --- Results / Chapter 3.2.2.1 --- Overexpressed Tau is phosphorylated and toxic in fly --- p.53 / Chapter 3.2.2.2 --- Coexpression of GSK3β/Shaggy or Cdk5 enhance Tau phosphorylation and Tau-induced toxicity --- p.57 / Chapter 3.2.2.3 --- Lithium suppresses Tau phosphorylation and Tau-induced toxicity --- p.64 / Chapter 3.2.3 --- Discussion --- p.68 / Chapter 3.3 --- Tau solubility properties in transgenic fly / Chapter 3.3.1 --- Introduction --- p.69 / Chapter 3.3.2 --- Results / Chapter 3.3.2.1 --- Coexpression of GSKlβ/Shaggy does not alter the sarkosyl solubility of Tau --- p.70 / Chapter 3.3.2.2 --- Coexpression of GSK3β/Shaggy causes a minor alteration of Tau solubility properties --- p.73 / Chapter 3.3.3 --- Discussion --- p.78 / Chapter 3.4 --- Tau aggregate formation in transgenic fly / Chapter 3.4.1 --- Introduction --- p.79 / Chapter 3.4.2 --- Results / Chapter 3.4.2.1 --- Tau aggregates are detected in aged transgenic flies --- p.80 / Chapter 3.4.3 --- Discussion --- p.82 / Chapter 3.5 --- Effect of Lithium on GSK3p/Shaggy-induced wing deformation / Chapter 3.5.1 --- Introduction --- p.83 / Chapter 3.5.2 --- Results / Chapter 3.5.2.1 --- Lithium rescues GSK3β/Shaggy-induced wing deformation --- p.84 / Chapter 3.5.3 --- Discussion --- p.86 / Chapter Chapter 4 --- General discussion --- p.87 / References --- p.92

Fundamental to the development of metazoa and plants is the capacity of cells to respond to transient intrinsic and extrinsic signals with permanent changes in gene expression that control cellular fates. A paradigmatic example of this process is observed in the case of the conserved, master regulatory HOX genes. The HOX genes are activated early in embryogenesis in combinatorial ON/OFF codes of expression, which act to specify and maintain segment identity in animals. In Drosophila, the “choice” of HOX code is controlled by transiently expressed transcription factors, while the “memory” of that choice is maintained in all future descendant cells through the action of the evolutionarily ancient Polycomb Group (PcG) gene family. The products of the PcG genes function in large, multimeric enzyme complexes known as Polycomb Repressive Complexes (PRCs) that are targeted to the HOX loci by cis-acting Polycomb Response Elements (PREs). Anchored at PREs, the PRCs catalyze a variety of chromatin modifications, most notably the trimethylation of histone H3 at lysine 27 (H3K27me3) by PRC2. These chromatin modifications are thought to both carry the memory of the HOX OFF code through DNA replication and to maintain transcriptional repression. In addition to the HOX genes, the PcG regulates hundreds of other important developmental control genes, the majority of which do not adopt heritable patterns of ON/OFF expression but instead are more dynamically expressed. This poses the question of how PcG activities control such diverse modes of gene expression. To investigate how PRE-anchored PRCs maintain heritable patterns of HOX gene expression, we have generated a transgenic lacZ reporter of the classical HOX gene Ultrabithorax (Ubx). Composed of minimal Ubx enhancer and promoter elements required to recapitulate the regulation of the native Ubx gene, the transgene contains the Ubx PRE embedded within a genetically labeled Flp-out cassette. H3K27me3 is deposited throughout the transgene in a manner that depends on the presence of the PRE. By excising the PRE in the cells of the wing imaginal disc where the transgene, like native Ubx, is heritably repressed, we are able to monitor the consequences of the loss of PRE-anchored PRC2 on both the inheritance of H3K27me3 and OFF state. We demonstrate that loss of the OFF state following PRE excision is correlated with the cell division-coupled dilution of H3K27me3. Further, by directly manipulating PRC2 activity of the H3K27 substrate, we demonstrate a causal relationship between the dilution of H3K27me3 nucleosomes and the number of times a cell can divide while maintaining the OFF state following PRE excision. In addition, we identified Ubx-lacZ transgene insertions that deviate from the classical patterns of heritable expression characteristic of the HOX genes in novel and informative ways. Our analysis of these insertions supports the view that PcG dependent chromatin modifications impose a quantitative rather than qualitative repressive influence on a gene’s promoter, with the promoter’s activity being determined within the context of other regulatory inputs. Similarly, contrary to classical view, we demonstrate that transcription too plays a quantitative role in determining whether or not a HOX locus adopts the heritable ON state. Together, our work suggests that the activities of the PcG confer a generic repressive influence on target loci. We posit that this influence is capable of maintaining heritable patterns of repression, as in the case of the HOX genes, because these loci have undergone stringent selection against enhancers capable of overcoming the repression mediated by the PcG. The absence of such strong activating inputs, together with the capacity of H3K27me3 to confer locus specific memory of the OFF state, allows for heritable patterns of repression. We propose that this is a special, albeit essential, attribute of the HOX genes. In contrast, most target genes have evolved to integrate repressive PcG chromatin modifications within the context of activating inputs that can override them. In these contexts, we propose that the PcG performs the role of a more general repressor, ensuring that repression is only overridden in those cells receiving peak activating cues. In this way the system may perform an essential role in conferring spatial and temporal robustness to gene expression programs.